Low profile valve and balloon catheter

ABSTRACT

A low profile inflation valve includes a first tube having a lumen and at least one region of decreased inner diameter, and a structure, which may be a tube, movably located inside the lumen. The region of decreased inner diameter of the first tube forms a seal with a portion of the structure. A method of making a low profile inflation valve using a first tube and second tube comprises the steps of creating an aperture in at least one side of the second tube; placing the second tube inside the first tube, the first tube being made of thermoplastic material; applying heat to a localized area of the first tube; and compressing the first tube to form a region of reduced internal diameter, the reduced diameter forming a seal with the outside diameter of the second tube.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation in part of application Ser. No.08/594,714 filed Jan. 31, 1996 abandoned.

BACKGROUND OF THE INVENTION

This invention relates to the field of medical apparatus. Morespecifically, this invention pertains to a low profile valve for usewith medical catheters.

Catheters are commonly used for a multitude of medical procedures. Manyprior art intravascular medical assemblies which incorporate catheterslack simple, effective means for regulating the pressure in the catheteror maintaining a pressure difference between the elements of the system.In addition, it is often difficult to control the flow of a fluidtraveling in the catheter.

Valves are commonly used in an attempt to address these problems.However, many prior art valves increase the profile of existingintravascular medical assemblies. This makes exchange of variousintravascular apparatus, such as sheaths, balloons and guides, over thevalve either difficult or impossible. A device that is small enough tobe used intravascularly and effectively controls the pressure inside thecatheter would be a great improvement in the art.

SUMMARY OF THE INVENTION

In one aspect, the low profile inflation valve of the present inventioncomprises a first tube having a lumen and at least one region of a firstlength with decreased inner diameter, a second tube slidably engagedwith the lumen of the first tube, the second tube having a lumen and aclosed distal end extending distally past said region of decreased innerdiameter of the first tube, the second tube also having at least oneaperture allowing passage of fluid from the lumen of the second tube tothe lumen of the first tube and a stop attached to the second tubedistally of the aperture, the stop having a transverse dimension greaterthan the decreased inner diameter of the first tube.

In the second aspect, the low profile inflation valve of the presentinvention comprises a first tube having a lumen that is closed at itsdistal end, the first tube also comprises at least one region with adecreased inner diameter and a second tube located inside the firsttube, the second tube having a lumen and a closed distal end, the secondtube also having at least one aperture located near its distal end, atleast a portion of the second tube extending past the region ofdecreased inner diameter of the first tube when the valve is in an openposition, wherein the region of decreased inner diameter of the firsttube forms a seal with the outer diameter of the second tube and blocksthe aperture when the valve is in a closed position.

In the third aspect, the present invention comprises a balloon catheterassembly comprising a low profile inflation valve comprising a firsttube having a lumen with a closed distal end, the first tube also havingone region with a decreased inner diameter, a second tube located insidethe first tube, the second tube having a lumen and a closed distal endextending distally past said region of decreased inner diameter of saidfirst tube, the second tube also having at least one aperture allowingpassage of fluid from the lumen of the second tube to the lumen of thefirst tube when the valve is in an open position, a stop attached to thesecond tube distally of the aperture, the stop having a transversedimension greater than the decreased inner diameter of the first tube,and an elastomeric balloon in fluid communication with the lumen of saidfirst tube distally of the region of decreased inner diameter.

In the fourth aspect, the present invention comprises a method of makinga low profile inflation valve using a first and second tube comprisingthe steps of creating an aperture in at least one side of a second tube,placing the second tube inside a first tube, the first tube being madeof thermoplastic material, applying heat to a localized area of thefirst tube, and compressing the first tube to form a region of reducedinternal diameter, the reduced diameter forming a seal with the outsidediameter of the second tube.

In the fifth aspect, the present invention comprises a method of makinga balloon catheter and valve assembly comprising the steps of supplyinga balloon catheter having a balloon and an inflation lumen, providing ahypotube having at least one aperture located near its distal end, thehypotube also having a stop attached to its distal end, inserting thehypotube into the inflation lumen of the balloon catheter, loading ateflon sleeve onto the outer diameter of the catheter, the sleeve havingan inner diameter that is larger than the outer diameter of thecatheter, loading the catheter-hypotube-sleeve assembly into aresistively heated die, heating the assembly to just above the softeningpoint of the catheter until the catheter wall in the region of thesleeve is softened, compressing the assembly in the region of the sleeveto form a region of reduced internal diameter and cooling the assembly.

In the sixth aspect, the present invention comprises a method of makinga tube with a region of decreased internal diameter comprising the stepsof applying heat to a localized area of a tube sufficient to soften thetube wall material in that region and compressing the tube, therebycausing the tube wall in the heated region to form said region ofdecreased internal diameter.

In the seventh aspect, the present invention comprises a low profileinflation valve comprising a first tube having a lumen and at least oneregion with a decreased inner diameter, and a structure movably locatedinside the first tube, wherein the region of decreased inner diameter ofthe first tube forms a seal with a portion of the structure.

In the eighth aspect, the present invention comprises a low profileinflation valve located inside a balloon catheter that enables a user tomaintain the balloon in an inflated state and exchange other medicalapparatus over the catheter.

In the ninth aspect, the invention comprises a valve having a maximumouter profile of about 0.3 cm.

One of the many advantages of the low profile valves of the presentinvention is that they provide a simple, effective means for regulatingthe pressure in a catheter or maintaining a pressure difference betweenthe elements of a system. A second advantage is that these valves enablea user to control the flow of fluid in the catheter. In addition, thesevalves are small enough to be used intravascularly. Furthermore, whenused in a balloon catheter, they enable a user to maintain the balloonin an inflated state while exchanging other medical apparatus over thecatheter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional side view of the first preferred embodimentof the low profile inflation valve of the present invention in theinflation position.

FIG. 2 is a cross-sectional front view of the valve of FIG. 1 takenalong the line 2--2 of FIG. 1.

FIG. 3 is a cross-sectional side view of the valve of FIG. 1 in theclosed position.

FIG. 4 is a cross-sectional front view of the valve of FIG. 3 takenalong the line of 4--4 of FIG. 3.

FIG. 5 is a cross-sectional side view of a second preferred embodimentof the low profile inflation valve of the present invention in theclosed position.

FIG. 6 is a cross-sectional side view of a third preferred embodiment ofthe low profile inflation valve of the present invention in theinflation position.

FIG. 7 is a cross-sectional side view of a fourth preferred embodimentof the low profile inflation valve of the present invention in theclosed position.

FIG. 8 is a cross-sectional side view of a fifth preferred embodiment ofthe low profile inflation valve of the present invention in an openposition.

FIG. 9 is a cross-sectional side view of a sixth preferred embodiment ofthe low profile inflation valve of the present invention in the closedposition.

FIG. 10 is a cross-sectional side view of a seventh preferred embodimentof the low profile inflation valve of the present invention in a closedposition.

FIG. 11 is a cross-sectional side view of the valve of FIG. 10 in anopen position.

DETAILED DESCRIPTION OF THE DRAWINGS AND PREFERRED EMBODIMENTS OF THEINVENTION

Referring initially to FIG. 1, a preferred embodiment of the low profileinflation valve 10 of the present invention is disclosed. Asillustrated, the valve 10 includes a first tube 20. In the preferredembodiment, the first tube 20 is part of a catheter. Thus the secondtube provides a structure that is moveable in a direction in line withthe axis of the lumen 22 between a first position in which fluid flow isprevented and a second position in which fluid flow is allowed. Thefirst tube 20 has a central lumen 22 and a region of a first length ofdecreased inner diameter 24. The lumen need not have a circularcross-section. As used herein, the term "decreased inner diameter"includes a decreased cross-sectional area where the lumen is not round.The length of the region 24 may vary considerably. Preferably, theregion of decreased inner diameter 24 is between about 0.1 and about 2.0cm long. In the preferred embodiment, the first tube 20 has an outerdiameter that is uniform on both sides of and in the region of decreasedinner diameter therefor.

The valve 10 also includes a second tube 30 slidably engaged within thelumen 22 of the first tube 20. The second tube 30 also has a lumen 32and a closed distal end 34. The second tube 30 also has at least oneaperture 36 located near its distal end 34. When the valve 10 is fullyassembled, the aperture 36 allows passage of fluid from the lumen 32 ofthe second tube 30 to the lumen 22 of the first tube 20. The second tube30 is precisely situated inside the first tube 20 so that at least aportion of the second tube 30 extends distally past the region ofdecreased inner diameter 24 of the first tube 20. The region ofdecreased inner diameter 24 of the first tube 20 and the outer diameterof the second tube 30 form a seal. Thus the second tube provides astructure that is moveable in a direction in line with the axis of thelumen 22 between a first position in which fluid flow is prevented and asecond position in which fluid flow is allowed. Because the second tube30 is slidably engaged in the first tube 20, in the preferredembodiment, the valve 10 also has a stop 40 attached to the second tube30 distally of aperture 36. In the preferred embodiment, the outsidediameter of the first tube 20 is between about 0.03 and about 1.0 cm,preferably between about 0.07 and about 0.2 cm, the inside diameter ofthe tube 20 is between about 0.03 and about 1.0 cm, preferably about0.03 and about 0.2 cm, except in its region of reduced diameter, wherethe inside diameter is between about 0.03 and about 1.0 cm, preferablyabout 0.03 and about 0.2 cm. In the preferred embodiment, the secondtube 30 has an outside diameter the same as the inside diameter of theregion of decreased inner diameter of the first tube 20 and an insidediameter of between about 0.03 and about 1.0 cm, preferably betweenabout 0.03 and about 0.2 cm. In the preferred embodiment, the stop 40 islocated approximately 0.1-4.0 cm from the aperture 36 in the second tube30, more preferably about 1.3 cm and most preferably about 0.64 cm. Thestop 40 has a transverse dimension greater than the decreased innerdiameter of the first tube 20 and thus limits the distance of proximaltravel of the second tube 30. The catheter preferably also includes apolymeric balloon 60. The balloon 60 may be a separate componentattached to the first tube 20, or it may be blown out of the first tube20. If the balloon 60 is a separate component, the first tube 20contains a balloon inflation aperture 26 which permits fluid to travelinto the balloon 60 from the catheter lumen 22, and vice versa.

The low profile inflation valve 10 of the present invention mayaccomplish various functions depending on the position of aperture 36.Thus, the valve 10 may be used to inflate a balloon 60, to retain thepressure inside the balloon 60 or to deflate the balloon 60. Forexample, in FIGS. 1 and 2, the second tube 30 is pushed forward by theoperator so that aperture 36 is positioned distally of the region ofreduced inner diameter 24 of the first tube 20. In this position, fluidthat is pumped into the lumen 32 of the second tube 30 exits the secondtube 30 through aperture 36 and enters the catheter lumen 22. The fluidtravels through the catheter lumen 22 until it reaches a ballooninflation aperture 26. The inflation fluid exits the catheter lumen 22through the balloon inflation aperture 26 and thus inflates the balloon60. Note that the valve could also be designed so that the second tube30 is pulled backward by the operator when inflating or deflating theballoon. Again, the aperture 36 resides within a region of reduced innerdiameter 24 until inflation or deflation is necessary. Such a design mayincorporate two or more areas of reduced internal diameter.

When the pressure inside the balloon 60 reaches the desired level, theoperator moves the second tube 30 in the proximal direction such thataperture 36 is positioned within the region of reduced inner diameter 24of the first tube 20 or proximal to the region of reduced inner diameter24 of the first tube. As most clearly depicted in FIG. 3, the stop 40attached to the second tube 30 limits the distance of proximal travel ofthe second tube 30. FIG. 4 illustrates the position of the aperture 36against the wall of the first tube 20. Because a low pressure seal isformed between the outer diameter of the second tube 30 and the regionof reduced diameter 24 of the first tube 20, the fluid is prevented fromexiting the catheter lumen through aperture 36.

In the event that it is no longer necessary to maintain the balloon 60in an inflated state, the user returns the valve 10 to the positiondepicted in FIG. 1. Thus, the second tube 30 is moved in the proximaldirection so that aperture 36 is located distally of the region ofdecreased inner diameter 24 of the first tube 20. When pressure isreleased from the lumen of the second tube 30, the inflation fluid willexit the balloon 60 and enter the catheter lumen 22 through the ballooninflation aperture 26. The inflation fluid travels proximally and entersthe lumen 32 of the second tube 30 through aperture 36. Thus, theballoon 60 is deflated.

The first tube 20 is preferably made of thermoplastic material. Morepreferably, the first tube 20 is Pebax, manufactured by Atochem.

The second tube may be made of any biocompatible metal or biocompatiblepolymer. The second tube 30 is preferably made of a rigid polymer ormetal, more preferably a high temperature polymer, and most preferablystainless steel or Nitinol. Examples of high temperature polymersinclude, but are not limited to, PEEK, polyamide, and Teflon. When thevalve is made by the preferred method described below, the second tube30 must have a higher melting point than the first tube 20.

The stop 40 may be formed by any material and any method that gives aportion of the second tube an outer diameter greater than the reducedinner diameter of the first tube. Examples of such materials include butare not limited to metals and various polymers. For example, the stopmay be a piece of coil or short section of tube glued or soldered ontothe second tube.

The invention also includes the method of making the above described lowprofile inflation valve 10 using a first 20 and second tube 30.Initially, the distal end of the second tube 30 is sealed. Sealing maybe accomplished by any method currently known in the art. Preferably,either before or after the end 34 is sealed, an aperture 36 is createdin at least one side of the second tube 30. The aperture 36 shouldpreferably be located between about 0.1 and about 2.0 cm from the distalend of the second tube 30, more preferably about 0.3 to about 1.7 cmfrom the distal end of the second tube 30 and most preferably about 0.5cm from the distal end of the second tube 30. Then the second tube 30 isplaced inside the first tube 20. In the preferred embodiment, the firsttube 20 is a balloon catheter. If the compositions of the first 20 andsecond 30 tubes create the potential for the tubes to stick together,the second tube 30 may be covered with a lubricous sleeve or coatingbefore it is placed in the first tube 20. Preferably, the lubricouscoating is permanently sprayed on the tube. Examples of suitablecoatings include, but are not limited to, Teflon, silicone and HPC(hydrophilic coating). Alternately, a sleeve made of similar material,such as Teflon, could be placed onto the outer diameter of the secondtube. The sleeve must have an inner diameter that is larger than theouter diameter of the second tube. If the first tube is a ballooncatheter, it is preferred that the distal end of the sleeve isapproximately 0.25 in. from the proximal end of the balloon.

Next, heat is applied to a localized area of the first tube 20. Heatingmay be accomplished by any method currently known in the art, includingbut not limited to direct current (DC), radiofrequency (RF), inductanceand infrared radiation (IR). For example, the first tube could be placedin a die. The die may be made of any material that will not be affectedby the heat applied to the working piece. After the first tube has beenheated to its softening point, it is compressed to form a region ofreduced internal diameter 24. Compression by any method known in the artis suitable. For example, longitudinal compression may be suppliedmanually or by a clamp. If manual longitudinal compression is the methodof choice, predetermined regions of the first tube 20 are manuallypressed towards each other. This pressure causes the softened wall ofthe first tube 10 to form a region of decreased internal diameter 24.Longitudinal compression is commonly employed when a sleeve has beenused so that the outer diameter of the first tube remains constant ordecreases. The tube 20 may also be compressed radially. If radialcompression is employed, the outer diameter of the shaft may decrease asthe region of decreased inner diameter is being formed. In either event,a seal is formed between the region of reduced internal diameter 24 ofthe first tube 20 and the outer diameter of the second tube 30.Furthermore, as shown in FIGS. 1, 3 and 4, the material making up ofdecreased inner diameter 24 is the same material that comprises the wallof the first tube 20. The region of decreased inner diameter ismonolithic with the wall material of the first tube. After the heatingand compressing steps, the valve assembly is allowed to air cool, oralternately, may be cooled using forced fluid flow.

Regardless of the technique used, the amount of heat applied and theduration of heating depend upon the composition of the first tube 20.The heat applied must be sufficient to soften the wall of the first tube20 without affecting the second tube 30. For example, if the first tube20 is made of Pebax (Polyether block amide), heating should occur atapproximately 335-370° F. for about 10-15 seconds.

There are many possible variations of the apparatus and method of thepresent invention. One variation alleviates the need for the separateelement acting as a stop 40 on the second tube 30. In this embodiment,the second tube 30 is a hypotube that is flared at its distal end, theflared portion comprising the stop 40.

Another variation of the preferred embodiment includes the use of awire. A wire may be used in conjunction with the above describedtwo-tube embodiment. For example, a stiffening wire could be attached tothe distal end of the second or inner tube 30. In this instance, thewire adds stiffness to the device but is not necessary for properorientation of the valve.

In another preferred embodiment a wire 170 is used instead of a secondor inner tube. Preferably, the wire is tapered at one end. FIG. 5 showsa push/pull design. This design also has a tapered wire 170 that fitswithin a tube lumen. The outer tube 120 has a region of decreased innerdiameter 124. This valve is open when the insert is pulled back to leavespace between the wire taper and the region of decreased inner diameter124. The valve is then closed by moving the wire 170 forward until thetaper fits tightly into the region of decreased inner diameter 124. Theinterference fit between the wire and the region of decreased innerdiameter 124 prevents the wire 170 from being pulled out of the firsttube 120. In the push/pull design, a stop (not shown) may also be usedto prevent the wire 170 from being pulled out of the outer tube 120.

FIG. 6 shows another embodiment of the pull/push wire design. In thisdesign, the taper on the wire 270 is distal to the region of reducedinner diameter 224. When the wire 270 is pushed forward there is roombetween the wire 270 and the outer tube 220 to allow fluid flow. Thevalve is then closed when the wire 270 is moved back so that the wiretaper fits tightly into the region of decreased inner diameter 224 onthe outer tube 220. At this point, the interference fit between the wireand the outer tube will prevent fluid flow between the two sides of thevalve.

It may not be desirable in some applications to taper the wire insert.In these circumstances, as depicted in FIG. 7, an additional tube ortapered tube 380 can be placed on the wire 370 to perform the samefunctions as the wire taper.

Another series of low profile valve designs, illustrated in FIGS. 8-11,use a spring and ball assembly. FIG. 8 shows a ball valve that uses apin 410 to pressurize and depressurize the system. There are two regions423 and 424 in which the inner diameter of the first tube 420 isdecreased. In this embodiment, the spring 490 is attached to the distalregion of reduced inner diameter 424. A ball 400 is attached to theopposite end of the spring 490. The spring's compressive forces forcethe ball 400 towards the proximal region of decreased inner diameter423. This is the position that the ball 400 and spring 490 exhibit undernormal conditions. During pressurization of the system, the pin 410 isinserted into the end of the device and pushes the ball 400 forward tothe position shown in FIG. 8 to allow fluid to flow around the ball 400and into the distal region. When the distal region has reached theproper pressure, the pin 410 is removed from the device. The compressiveforces in the spring 490 as well as the pressure in the system force theball 400 against the proximal region of decreased inner diameter 423. Atthis point, the system is supporting a pressure difference between thetwo sides of the valve. Depressurization of the system is accomplishedby reinserting the pin 410 and pushing the ball 400 forward until fluidcan escape out of the system.

The pressurization/depressurization pin 410 can be made in differentways. The pin 410 can be made as a solid wire that is smaller than theproximal region of decreased inner diameter. The fluid enters the systembetween the pin 410 and the inner diameter of the proximal region ofdecreased inner diameter. Another option is to use a hypotube with atleast one hole towards its distal end. The outer diameter of thehypotube should fit tightly into the region of decreased inner diameter.This pin would be inserted until the distal hole is beyond the region ofdecreased inner diameter. Fluid then would exit through this inflationhole around the displaced ball and into the system to be pressurized.

FIG. 9 depicts a ball-spring valve that does not use a pin to pressurizethe system. Fluid is injected into the proximal end of the device topressurize the system. The force of the fluid then forces the ball 500forward and allows the fluid to enter the distal side of the system.Once the force of inflation halts, the pressure in the system and theforce in the spring 590 force the ball 500 against the proximal regionof decreased inner diameter 523. Depressurization of the system isaccomplished by using a pin 510.

FIGS. 10 and 11 show yet another option for a ball-spring valve design.In this embodiment, two springs 691 and 692 are used to support the ball600. Pressurization is accomplished by either method described above.While holding pressure, the ball 600 is forced toward the proximalspring 691. There must be enough force on the ball 600 to close theloops of the proximal spring 691 and prevent fluid flow between theopposite sides of the device. As shown in FIG. 11, depressurization ofthe system is then accomplished using a depressurization pin 610.

The ball and springs of FIGS. 8-11 can be made of any suitable materialincluding, but not limited to, stainless steel, nitinol and polymers.The ball does not necessarily have to be spherical. It can be made inany shape that allows it to sit tightly and block the flow of fluidbetween the two sides of the system.

Other variations involve the method of creating a reduced region ofinner diameter. These variations may be beneficial when the valve willbe used in conjunction with a catheter body that is not suitable valvematerial. For example, an additional tube may be inserted into theproximal end of the catheter body. The additional tube can then be usedto form the region of decreased inner diameter. In this application, theinserted tube and the catheter body must have similar melting points.

Alternately, the valve material can be bonded or welded to the optimummaterial. After this is done, the region of reduced inner diameter canbe formed by any of the methods disclosed. The outer tube could also bemade using intermittent extrusion. This is a continuous extrusionprocess that can alter the durometer of tubing so that a heat weld wouldnot be necessary. With these methods (heat weld, adhesive bond, orintermittent extrusion), the material used for the valve can be placedanywhere along the shaft of the device.

Another option is to insert a tube into another tube without any furtherprocessing. The inner tube would form the region of decreased innerdiameter. Another option is to inject a material into the inner diameterof the first tube. Once the material is injected into the inner diameterit cures and secures itself to the inside of the outer tube.

Another possibility is to start with a relatively thick tube. To createa region of reduced inner diameter, a portion of the middle of the tubewould be left in its original state while both ends of the tube aredrawn out.

Additional options include using different tubes connected in series. Atube made of the valve material may be incorporated that has a smallerinner diameter than the rest of the tubing. The various pieces of tubingcan be bonded together using any means commonly used in the industryincluding, but not limited to, heat bonding and adhesive bonding.

Additional ways of creating a region of decreased inner diameter mayencompass necking the first tube. Necking may be accomplished using anymethod commonly known in the industry. The neck can be formed anywhereon the shaft. What distinguishes the neck from most of the other designsdisclosed is that the outer diameter of the tube is decreased during thenecking process just as it is during radial compression. An alternateoption is to force the material into a hot die so that is closes downthe inner diameter of the tubing. This design can only be used if thevalve portion is on the end of the shaft. A further option for forming areduced inner diameter is to place a heat shrinkable material (i.e.Teflon, polyester, etc.) onto the outer diameter of a tube andselectively heat the heat shrinkable material and the correspondingportion of the tube. Preferably, the shrink tube is heated by infraredradiation. The heat shrinkable material will condense, thereby forming aregion of decreased inner diameter.

Each of the embodiments of FIGS. 1-11 can be made to have a maximumouter profile of about 0.3 cm. Valves of such small outer profile areunique. They make it possible to use the valve in intravascular medicaldevices. In addition, they provide a simple, effective means forregulating the pressure in or maintaining a pressure difference betweendifferent elements in a medical system. When these valves areincorporated into a balloon catheter, they enable a user to maintain theballoon in an inflated state and exchange other medical apparatus overthe catheter.

There are many advantages to the preferred embodiment of the low profileinflation valve of the present invention. Firstly, the new valve has alow profile and therefore enables exchange of various intravascularapparatus over the valve. When the valve is incorporated into a ballooncatheter, the valve permits exchange of other devices over an inflatedballoon. Secondly, as clearly illustrated in FIG. 3, the seal formedbetween the region of deceased inner diameter of the first tube and theouter diameter of the second tube effectively controls the pressureinside of a balloon because the inflation fluid is prevented fromexiting the catheter lumen through the aperture in the second tube.Thirdly, the valve is easy to use and may be operated by one person likea onehanded stopcock. In addition, the valve can be made to leak abovecertain pressures and therefore becomes pressure limiting. For example,if the balloon is over inflated, the valve will allow fluid to leakuntil the balloon pressure is in an acceptable range.

It should be appreciated that the apparatus and methods of the presentinvention are capable of being incorporated in the form of a variety ofembodiments, only a few of which have been illustrated and describedabove. The invention may be embodied in other forms without departingfrom its spirit or essential characteristics. The described embodimentsare to be considered in all respects only as illustrative and notrestrictive, and the scope of the invention is, therefore, indicated bythe appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

We claim:
 1. A low profile inflation valve comprising:a) a first tubecomprising a wall material and having a lumen; said first tube alsocomprising at least one region of a first length with a decreased innerdiameter, the region of decreased inner diameter being formed of thesame material as, and being a monolithic part of, the wall material ofthe first tube; and b) a second tube slidably engaged within the lumenof said first tube, said second tube having a lumen, said second tubeextending distally past said region of decreased inner diameter of saidfirst tube, said second tube also having at least one aperture allowingpassage of fluid from the lumen of the second tube to the lumen of thefirst tube when said valve is open, said at least one aperture beingblocked when said valve is closed; c) the valve having an outer profilenot exceeding about 0.3 cm.
 2. A combined balloon catheter and lowprofile inflation valve comprising:a) a balloon catheter having alongitudinally extending, non-branching shaft including a proximal endand a distal end with an inflatable balloon adjacent the distal end andan internal surface defining an inflation lumen between the proximal endand the distal end, the lumen being in fluid communication with theballoon such that fluid forced into the distal end of the lumen inflatesthe balloon; b) a structure disposed at the proximal end of thenon-branching shaft and located within the inflation lumen slideablebetween an open position and a closed position, the structure beingconfigured to cooperate with the internal surface of the lumen to allowfluid from outside of the catheter to flow through an aperture into thelumen when the structure is in said open position and to block fluidfrom flowing through the aperture when the structure is in said closedposition; and c) a control device outside of the lumen and connected tosaid structure by which an operator controls the position of thestructure within the lumen, the control device and structure being sizedsuch that a user may maintain the balloon in an inflated state andexchange other medical apparatus over the catheter.
 3. The combinedballoon catheter and low profile inflation valve of claim 2 furthercomprising a stop limiting the distance of proximal travel of thestructure.
 4. The combined balloon catheter and low profile inflationvalve of claim 2 wherein said control device has a larger diameter thansaid structure located inside the inflation lumen.